ARS | Publication request: SIMULTANEOUS DETECTION OF EDWARDSIELLA ICTALURI AND FLAVOBACTERIUM COLUMNARE BY DUAL IMMUNOFLUORESCENCE TEST

Submitted to: American Fisheries Society Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: August 10, 2006
Publication Date: August 31, 2006
Citation: Panangala, V.S., Shelby, R.A., Shoemaker, C.A., Klesius, P.H., Morrison, E.E. 2006. Simultaneous detection of Edwardsiella ictaluri and Flavobacterium columnare by dual immunofluorescence test. Proceedings of the 5th International Symposium on Aquatic Animal Health (American Fisheries Society, Fish Health Section). p. 208.

Technical Abstract: A rapid immunofluorescence test with fluorescent conjugated-antibodies having different spectral properties (Alexa Fluor 488-emitting green fluorescence and Alexa Fluor 594-emitting red fluorescence) was compared with standard bacteriological culture for simultaneous detection of bacterial fish pathogens Edwardsiella ictaluri (EI) and Flavobacterium columnare (FC). Three groups of experimentally infected channel catfish (Ictalurus punctatus Rafinesque) and a fourth group that acquired an aquarium-infection with F. columnare were tested. Kidney, brain and nares tissues from 101 fish were concurrently examined by both tests. Fish in the three experimentally infected groups yielded bacteria with which they were infected, while fish in the fourth group revealed F. columnare both by culture and IFA test. The IFA test compared favorably in sensitivity (for EI = 80.7%, and for FC = 87.2%) and specificity (for EI = 83.9% and for FC = 88.9%) with the standard bacteriological culture. The positive predictive value (for EI = 96.2% group I; 90.8% group II; and 93.7% groups I & II combined; for FC = 95.2% group II; and 95.3% groups II, III & IV combined) was high, while the negative predictive value (for EI = 66.7% group I; 31.3% group II, and 59.5% groups I & II combined; for FC = 73.7% group II and 72.7% groups II, III, & IV combined) was relatively low. The dual immunofluorescence test will serve as an efficient tool for rapid simultaneous detection of E. ictaluri and F. columnare in outbreaks of disease.